Chemiluminescence

ABSTRACT

A chemiluminescent system comprising (1) derivatives of a polycarbonyl compound substituted with at least one nitrogen-containing hetero group and which may have an alkanol or amine substituent, (2) a hydroperoxide compound, (3) a diluent, and (4) a fluorescer, said ingredients in combination producing visible chemiluminescent light and a process of producing such light.

This application is a continuation of Ser. No. 211,807, filed Dec. 23,1971 and now abandoned, which application was a division of Ser. No.844,657 filed July 24, 1969, now abandoned, which application was inturn a continuation-in-part of Ser. No. 547,782 filed May 5, 1966, nowabandoned.

The present invention relates to novel polycarbonyl compounds whichobtain chemiluminescent light when reacted with other necessarychemiluminescent reactants in the direct generation of light fromchemical energy. By "light" as referred to herein is meantelectromagnetic radiation at wavelengths falling between about 350 mμand about 800 mμ.

The art of generating light from chemical energy, i.e.chemiluminescence, is continually in search of compositions which whenreacted substantially improve the intensity and lifetime of lightemission contrasted to known chemiluminescent compositions andreactions. Obviously, improved compositions are constantly in demand foruse as signal devices, for area illumination, etc.

It is an object of this invention to obtain a chemiluminescentcomposition and a process employing said composition whereby a highefficiency may be obtained in the conversion of chemical energy intolight.

Another object is to obtain a chemiluminescent compound which produceslight over an extended period of time.

Another object of this invention is to obtain a chemiluminescentcomposition which attains light of substantially higher intensity andwith a greater degree of quantum efficiency than has been obtained withformer chemiluminescent compositions.

Another object of this invention is to obtain a chemiluminescentcomposition which may be employed to obtain light by a process which ismechanically simple and which is economically inexpensive.

Another object of this invention is to obtain a chemiluminescentreactant which is stable over a long period of time and wich may besubsequently reacted to obtain chemiluminescent light.

Another object of this invention is to obtain a chemiluminescentreactant which when reacted will obtain chemiluminescent light by aprocess which is not hazardous.

Another object is to obtain a composition characterized by its abilityto undergo partial chemiluminescence, followed by reversal to asubstantially non-chemiluminescent state.

Another object is to obtain a composition characterized by acontrollable (1) length of duration of chemiluminescence and (2)intensity of chemiluminescent illumination.

Another object is to obtain a process of regulating intensity andduration of chemiluminescence.

Other objects of this invention become apparent from the above andfollowing disclosure.

The term "tautomerism" as used herein means the coexistence of two ormore compounds that differ from each other only in the position of oneor more mobile atoms and in electron distribution, a typicalillustrating example of tautomeric forms being: ##SPC1##

The term "rearrangement" as used herein means the conversion of acompound to one or more different compounds that differ from each other,and from the starting compound in the position of one or more mobileatoms and in electron distribution. The term rearrangement also includesany subsequent or concurrent conversion of the compounds involved in arearrangement (as defined above) to their conjugate acid or base or asalt of the conjugate acid or base.

The term "aromatic compound" as used herein includes both benzenoidcompounds and heterocyclic compounds which are characterized bysubstantial resonance energy ( >5 kcal per mole) and by the tendency toundergo substitution reactions with reagents that ordinarily add to adouble bond. Accordingly, monocyclic, polycyclic, and heterocycliccompounds are also included.

The term "aryl group" as used herein means a group which is derived froman aromatic compound by the removal of one or more atoms.

The term "chemiluminescent reactant", as used herein, means (1) amixture which will result in a chemiluminescent reaction when reactedwith other necessary reactants in the processes as disclosed herein, or(2) a chemiluminescent composition.

The term "fluorescent compound", as used herein, means a compound whichfluoresces in a chemiluminescent reaction, or a compound which producesa fluorescent compound in a chemiluminescent reaction.

The term "chemiluminescent composition", as used herein, means a mixturewhich will result in chemiluminescence.

The term "admixing", as used herein, means "reacting" or sufficientlybringing together component reactants to obtain a chemiluminescentreaction.

The term "hydroperoxide compound" as used herein is limited to peroxidecompounds having at least one HOO-- group, or a compound which uponreaction produces a compound with such a group.

The term "peroxidic groups", as used herein, represents "HOO--","ROO--", or ##EQU1## "R'" is defined for the polycarbonyl compoundbelow, while R is a substituent such as alkyl, cycloalkyl,α-hydroxyalkyl, substituted alkyl, for example.

The term "diluent", as used herein, means a solvent or a vehicle whichwhen employed with a solvent does not cause insolubility.

The term "peroxide compound", as used herein, also includes compoundswhich upon reaction produce the peroxide group.

The term "hydrogen peroxide compound" includes (1) hydrogen peroxide and(2) hydrogen peroxide-producing compounds.

The objects of this invention are obtained by the employment, with othernecessary chemiluminescent reactants, of a composition of the formula:

    A -- B -- C

in which B is a polycarbonyl group which has a substituent of each of Aand C, B being of the formula: ##EQU2## where n is an integer of atleast one, in which A is a Q'hydro-Q² oxo-substitutednitrogen-containing aromatic compound onto which one terminal carbonylgroup of said B is substituted at a nitrogen atom of said A is aQ'hydro-Q² oxo-substituted nitrogen-containing aromatic compound inwhich each of Q' and Q² is a group occurring at least once and the valueof Q' is greater than, and preferably twice the value of Q², in which Q'describes the number of hydro substituents present on the aromaticgroups, and Q² describes the number of oxo substituents present on thearomatic group, said A being represented by the structure: ##EQU3## saidQ' and Q² being as above recited, and ##EQU4## representing a mono- orpolycyclic nitrogen-containing heterocyclic group, m and p beingintegers of at least one, m being greater than p, and m preferably beingat least twice p, and in which said C is a compound selected from thegroup consisting of (1) said A, (2) an alcohol of the formula R' -- O --H forming an ester of a carbonyl group of said B, in which R' isselected from the group consisting of (a) aryl, (b) electronegativelysubstituted alkyl, (c) heterocyclicalkylaryl, and (d) unsaturated alkyl,and (3) an amine which forms an amide with a terminal carbonyl group ofsaid B and which amine is selected from the group consisting of:##EQU5## (c) R⁴ --N=N--H, and (d) strongly electronegativelyN-substituted (substituted or non-substituted) nitrogen-containingheterocyclic compounds, where the N- is attached directly to a terminalcarbonyl carbon of said B, typical N-substituted nitrogen-containingheterocyclic compounds including compounds of the formula: ##SPC2##

where any one or more of the heterocyclic compounds may include alkylsubstituents and typical electronegative substituents such as above athrough e including cyano, halogen, sulfo, oxygen-substitutedphosphorous substituents, etc.; where R⁴ is selected from the groupconsisting of hydrogen and the members of R³, where R³ is selected fromthe group consisting of alkyl, aryl, cycloalkyl, heterocyclic,polycyclic, amino, and alkyl- or aryl or acyl-substituted aminosubstituents; where R² is selected from the group consisting of themembers of both R⁴ and the following electronegatively substitutedgroups: (a) mono, poly-, and aryl groups substituted further by at leastone electronegative group, where the electronegative substituent of saidaryl group is typically a member selected from the groups consisting of(I) nitro, (II) a halogen, provided at least three halogen substituentsare present in the amide, (III) oxygenated-sulfur substituents such as##EQU6## and ##EQU7## where R⁵ and R⁶ are each selected from the groupconsisting of alkyl, aryl, cycloalkyl, heterocyclic, and polycyclicsubstituents, and where R⁷ and R⁹ are each selected from the groupconsisting of hydrogen and the members of R⁵ defined above, (IV) cyano,(V) a polyfluoroalkyl substituent such as F₃ C--, F₅ C₂ --, F₃ H₂ C₂ --,F₂ CH--, and F₂ C₂ H₂ (CH₃)--, F₃ C₂ H₂ --, F₂ C₃ H₅ --, etc. and (VI)an acyl substituent of the formula ##EQU8## where R⁹ is defined the sameas R⁷, provided that said aryl group includes a sufficient number ofelectronegative members to obtain an acidity of the amine at least asgreat as the acidity of 4-nitroaniline, (b) a polyfluoroalkylsubstituent as defined above, and (c) an acyl substituent as definedabove; where Z is a member selected from the group consisting of (a)cyano (i.e., NC--), (b) nitrosyl (ON--), (c) nitroxyl (O₂ N--), (d)oxygenated-sulfur substituents such as ##EQU9## and ##EQU10## where R⁵ ,R⁶ are defined above and R^(1o) and R¹¹ are each defined the same as R⁵,and (e) oxygen-substituted phosphorous substituents such as (R¹²)₂ P--,and (R¹³ O)₂ P--, where R¹² and R¹³ are defined the same as R⁴.

In the preferred embodiment C is the same as A, thereby forming thepreferred symmetric polycarbonyl compound.

In the preferred embodiment of the generic formula, the compounds whichobtain optimum chemiluminescence when reacted are characterized by arearrangement to an ester which is more reactive and produceschemiluminescence more efficiently.

In a preferred embodiment of the generic formula, n ranges from about 1to about 4.

We have unexpectedly discovered that the objects of this invention areobtained by the preparation of any one of the above generic compounds,and subsequently admixing the above generic compound of this inventionwith other necessary reactants to obtain chemiluminescence, the otherreactants including at least one of each of hydroperoxide, a diluent,and a fluorescer (fluorescent compound). Moreover, unexpectedly superiorresults are obtained by including at least sufficient acidic material toobtain an acid pH, whereby a more intense chemiluminescent light isobtained substantially proportional to the increased acidity of thereaction mixture. Also it was unexpectedly discovered that lightintensity may be substantially quenched or "suspended" by the additionof alkaline material to the acidic mixture. It is also unexpectedlydiscovered that light intensity and the quantum efficiency may besubstantially increased by increasing the concentration of the genericcompound (of this invention) in the reaction mixture. An increase in theconcentration of the generic compound and/or a lowering of the pH, inthe reaction mixture, obtains a substantially increased intensity ofchemiluminescent light. If solely the pH of the reaction mixture islowered, the lifetime of the chemiluminescent reaction will beshortened. The addition of an alkaline material to an acidic reactionmixture retards the rate of reaction presumably by retarding orpreventing rearrangement of the remaining stable polycarbonyl compoundand thereby increase the duration of time during which chemiluminescencemay be obtained. Subsequent addition of acid material to an alkalinemedia increases the rate of reaction. Depending upon the combination ofvariable factors as discussed above, the intensity or reaction and therate of reaction may be extended over a period of 12 hours or more.

In the preferred embodiment, bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal isemployed, and is reacted in the presence of an acidic material, wherethe reaction media includes also a hydroperoxide and a fluorescer.

In any of the embodiments of this invention, as shall be furtherdiscussed below, the fluorescer or the hydroperoxide may each or both beintimate parts of other reactant molecules. A typical example is asituation in which the fluorescent material is an intimate part of thebis(Q'hydro-Q² oxo substituted-nitrogen-aryl)polycarbonyl molecule.

Typical Q'hydro-Q² oxo substituted nitrogen containing aromaticcompounds comprise: (I) compounds that contain at least one nitrogen asa hetero atom such as 1,2-dihydro-2-oxopyridine or 2-hydroxy-pyridinethe tautomeric form.

A typical compound of this invention in which A and C are each aderivative of the tautomeric compoundsymmetric-1,2-dihydro-2-oxopyridine and n is 1, is represented by theformula: ##SPC3##

Rearrangement in the presence of an acid HX (acid) may result in theformation of one or more of the following compounds: ##SPC4##

However, the invention disclosed herein is not to be restricted to thistheory, except as limited in the appended claims.

Other examples of the A (as defined above) are Q'hydro-Q² oxosubstituted nitrogen containing aromatic compounds as follows:

(1) compounds that contain one oxo substituent as: e.g.,1,2-dihydro-2-oxoquinoline, 1,5-dihydro-5-oxoquinoline,2,3-dihydro-3-oxoisoquinoline, etc. and ##SPC5##

(2) compounds that contain more than one oxo-substituent as: e.g.,1,2,3,4-tetrahydro-2,4-dioxopyridine, hexahydro-2,4,6-trioxopyridine,1,2,3,4-tetrahydro-2,4-dioxoquinoline.

Other typical Q'hydro-Q² oxo substituted nitrogen containing aromaticcompounds that contain at least one nitrogen and at least anotherheteroatom than nitrogen, include:

1. compounds that contain one oxo substituent as: e.g.,2,3-dihydro-3-oxoisothiazole, 2,3-dihydro-2-oxooxazole,

2. compounds that contain more than one oxo substituent e.g.,2,3,4,5-tetrahydro-3,4-dioxoisoxazole.

Typical Q'hydro-Q² oxo substituted nitrogen containing aromaticcompounds that contain more than one nitrogen heteroatom include:

1. compounds that contain more than one nitrogen heteroatom but which:

a. contain only one oxo substituent e.g.,1,2-dihydro-2-oxo-1,3,5-triazine, 1,6-dihydro-6-oxopentazine,

b. contain more than one oxo substituent e.g.,hexahydro-2,4,6-trioxo-1,3,5-triazine;

2. compounds than contain more than one nitrogen heteroatom and at leastanother heteroatom other than nitrogen but which:

a. contain only one oxo substituent e.g., 2,3-dihydro-3-oxofurazan, 4,5-dihydro-5-oxo-1,2,3,4-oxatriazole,

b. contain more than one oxo substituent e.g.,tetrahydro-2,5-dioxo-1,3,4-oxadiazole, tetrahydro-3,4-dioxofurazan.

All the typical Q'hydro-Q² oxo substituted nitrogen containing aromaticcompounds described above may be substituted further by alkyl aryl andcyclic alkyl groups and by groups such as R', R², R³ and R⁴, alreadydefined above.

In the typical formula described above, the C may also represent any oneof the following group of compounds: (1) an alcohol of the followingtypical formula:

    R' -- O -- H

where R represents:

A. electronegatively substituted alkyl groups such as those substitutedat the α or β positions by:

a. by halogen: e.g., trifluoromethyl-, trichloro-methyl-,perfluoroethyl-, perfluorodecyl-, 1,1,2,2-tetrafluorocyclohexyl-.

b. by carboxy groups: e.g., carboxymethyl-, carboxyethyl-;

c. by heterocyclic groups: e.g., pyridylethyl-, furylmethyl-,tetrahydrofurylpropyl-, acridinylethyl-;

d. by sulfo groups: e.g., sulfomethyl-;

B. aryl groups: e.g., phenyl-, naphthyl-, or substituted aryl groups bytypical substituents such as:

a. by halogen: e.g., pentafluorophenyl-, dichlorophenyl-,dibromophenyl-;

b. by acyloxy groups: e.g., benzoyloxyphenyl-;

c. by carbonyl groups: e.g., formylphenyl-, acetylphenyl-;

d. by carboxyl groups: e.g., carboxyphenyl-;

e. by nitro groups: e.g., 2,4-dinitrophenyl-, 4-nitrophenyl-;

f. by heterocyclic groups: e.g., pyridylphenyl-, tetrahydrofurylphenyl-;

g. by sulfo groups: e.g., 2-nitro-4-sulfophenyl-,2-nitro-4-sulfonaphthyl-;

h. by cyano groups: e.g., 4-cyanophenyl-;

C. heterocyclic groups: e.g., pyridyl-, furyl-, acridinyl-, orsubstituted heterocyclic groups by typical substituents such as:

a. by alkyl groups: e.g., methylpyridyl-;

b. by halogen: e.g., chloropyridyl-;

c. by acyloxy groups: e.g., acetoxypyridyl-;

d. by carbonyl groups: e.g., formylpyridyl-;

e. by carbonyl groups: e.g., carboxypyridyl-;

f. by alkoxy groups: e.g., methoxyfuryl-;

g. by amino groups: e.g., dimethylaminotetrahydrofuryl-;

h. by sulfo groups: e.g., sulfofuryl-;

i. by hydroxy groups: e.g., 2-hydroxypyridyl-;

D. unsaturated alkyl and cyclic alkyl groups: e.g., vinyl-, allyl,ethynyl-, cyclohexenyl-, isopropenyl-.

As stated above, C may be an amine. Typical illustrative amines are asfollows: ##SPC6##

The preferred compounds of the generic formula described above withinthe scope of Applicant's invention include a large number ofpolycarbonyl compounds of the glyoxal-type which may contain twocarbonyl groups. Such compounds may be typically represented by thefollowing formula: ##EQU11## in which A and C are each defined asdescribed above, and in which at least one hetero atom of A is anitrogen, provided that said A is characterized by a potentialrearrangement to form a heteroaromatic oxalic type ester upon reactionwith other necessary chemiluminescent reactants discussed above;however, it should be noted that both in the generic (A--B--C) compoundsof this invention and in the preferred polyoxal embodiments, more thanone heteroatom may be present in each of A and C, and the additionalheteroatom may be sulfur, phosphorous, etc.

Representative (but not exclusive) compounds falling within the aboveformula include: ##SPC7##

The hydroperoxide employed in the compositions and process of thisinvention may be obtained from any suitable peroxide compound. Forexample, the hydroperoxide may be employed as sodium peroxide.Alternatively, sodium perborate may be places in aqueous solutionwhereby a solution of hydrogen peroxide is obtained. Obviously, hydrogenperoxide or its solution may be employed. The peroxide employed may beobtained from anhydrous hydrogen peroxide compounds such as perhydrateof urea (urea peroxide), perhydrate of pyrophosphate (sodiumpyrophosphate peroxide), perhydrate of histidine (histidine peroxide),sodium perborate, and the like. Still another form in which the H₂ O₂may be provided in the composition is that of an anhydrous solution ofH₂ O₂ in a suitable solvent such as an ether, an ester, an aromatichydrocarbon, etc. of the type which would provide a suitable diluent forthe composition of this invention. Alternatively, the hydroperoxideemployed in the composition or process could be any compound having ahydroperoxidic group, such as hydroperoxide (ROOH) or a peroxy acid##EQU12## such as t-butyl hydroperoxide and perbenzoic acid. Wheneverhydrogen peroxide is contemplated to be employed, any suitable compoundmay be substituted which will produce hydrogen peroxide.

The hydroperoxide concentration may range from about 15 molar down toabout 10⁻ ⁵, preferably about 2 molar down to about 10⁻ ⁴ molar. Thegeneric compound of this invention may be added as a solid or inadmixture with a suitable solid peroxide reactant or in a suitablediluent, or alternatively dissolved directly in a solution containingthe peroxide reactant.

Typical diluents within the purview of the instant discovery are thosethat do not readily react with a peroxide, such as hydrogen peroxide,and which do not readily react with the polycarbonyl compound or withthe rearranged polycarbonyl compound.

Although the addition of water tends to quench the production ofchemiluminescent light according to the present invention, water canserve as a partial diluent up to substantial major percentages (morethan 50%). The term "water", as used herein, includes water-producingcompounds such as hydrates.

Any one or more suitable diluents may be included with or in the placeof the water, as long as the peroxide employed is at least partiallysoluble in one or more of the diluent(s), such as, for example, at leastone gram of H₂ O₂ per liter of diluent. The following are typicalillustrative examples of the diluents or solvents which may be singly orjointly employed: non-cyclic or cyclic ethers, such as diethyl ether,diamyl ether, diphenyl ether, anisole, tetrahydrofuran, dioxane, and thelike; esters such as ethyl acetate, propyl formate, amyl acetate,dimethyl phthalate, diethyl phthalate, methyl benzoate, and the like;aromatic hydrocarbons, such as benzene, xylene, toluene, and the like,acids such as acetic or propionic acids.

The fluorescent compounds contemplated herein are numerous; and they maybe defined broadly as those which do not readily react on contact withthe peroxide employed in this invention, such as hydrogen peroxide;likewise, they do not readily react on contact with the generic compoundof this invention. Typical suitable fluorescent compounds for use in thepresent invention are those which have a spectral emission fallingbetween 330 millimicrons and 800 millimicrons and which are at leastpartially soluble in any of the above diluents, if such diluent isemployed. Among these are the conjugated polycyclic aromatic compoundshaving at least 3 fused rings, such as: anthracene, substitutedanthracene, benzanthracene, phenanthracene, substituted phenanthracene,naphthancene, substituted naphthacene, pentacene, substituted pentacene,and the like. Typical substituents for all of these are phenyl, loweralkyl, chlorine, bromine, cyano, alkoxy (C₁ -C₁₆), and other likesubstituents which do not interfere with the light-generating reactioncontemplated herein.

Numerous other fluorescent compounds having the properties givenhereinabove are well known in the art. Many of these are fully describedin "Fluorescence and Phosphorescence", by Peter Pringsheim, IntersciencePublishers, Inc. New York, N.Y., 1949. Other fluorescers are describedin "The Colour Index", Second Edition, Volume 2, The AmericanAssociation of Textile Chemists and Colorists, 1956, pp. 2907-2923.While only typical fluorescent compounds are listed hereinabove, theperson skilled in the art is fully aware of the fact that this inventionis not so restricted and that numerous other fluorescent compoundshaving similar properties are contemplated for use herein.

It should be noted, however, that although a fluorescent compound isnecessary to obtain the production of light, the fluorescent compound isnot necessary to obtain a chemical reaction and chemical energy release.Also, a fluorescent generic compound of this invention, such asbis(9,10-dihydro-9-oxo-10 -acridinyl)glyoxal does not require a separatefluorescent compound to obtain light. Other typical fluorescent, genericcompounds include esters which form when C is of the generic formula oneof the following alcohols: (1) 2-carboxyphenol, (2)2-carboxy-6-hydroxyphenol, (3) 1,4-dihydroxy-9,10-diphenylanthracene,and (4) 2-naphthol. Thus, a reactant including a fluorescent genericcompound of this invention would thereby include at least onefluorescent compound.

It has been found that the molar (moles per liter of diluent)concentrations of the major components of the novel composition hereindescribed may very considerably. It is only necessary that components bein sufficient concentration to obtain chemiluminescence. Thebis(dihydrooxosubstituted-hetero-heteroaromatic)polyoxal molarconcentration normally is in the range of at least about 10⁻ ⁷ molar,preferably in the range of at least about 10⁻ ⁴ to about 5 molar; thefluorescent compound is present in the range from about 10⁻ ⁵ to about5, preferably about 10⁻ ⁴ to about 10⁻ ¹ molar; and the ether or otherdiluent must be present in a sufficient amount to form at least apartial solution of the reactants involved in the chemiluminescentreaction. There is no known maximum limit on the concentration of thegeneric compound of this invention which may be employed in thereaction, and as discussed above, intense chemiluminescent light may beobtained by employment of the high concentrations.

The ingredients of the composition of this invention, may be admixed ina single stage of admixing or in a sequence of steps of admixingingredients together or separately. Accordingly, alternativecompositions may be prepared which may be stored over a period of timeand which may be admixed with the final ingredient at a time when thechemiluminescent lighting is desired. For example, one such compositionwould be a composition which includes a generic compound of thisinvention and a fluorescent compound but which does not include aperoxide compound. Another alternative solid composition would be acomposition which includes a peroxide, but which does not include thefluorescent compound. Another alternative composition would be a solidcomposition which includes a solid generic compound of this inventionand a solid hydroperoxide compound, and which possibly additionallyincludes a solid fluorescent compound, but which does set include adiluent. Obviously, the preferred compositions which would be less thanall necessary components to produce a chemiluminescent light would be acomposition which would be substantially stable to a practical degreeover an extended period of time; otherwise, there would be no realadvantage in forming a chemiluminescent reactant to be employed in asubsequent chemiluminescent reaction.

The wavelength of the light emitted by chemiluminescence of thecompositions of this invention, i.e., the color of the light emitted,may be varied by the addition of any one or more energy transfer agents(fluorescers) such as the known fluorescent compounds discussed atlength above.

The wavelength of the light emitted by the composition of this inventionwill vary, depending upon the particular fluorescent component employedin the reaction.

Although in the process of obtaining chemiluminescent light according tothis invention, it is normally not necessary to employ a specific orderof sequence of steps in the adding of the individual ingredients of theinventive chemiluminescent composition, it has been found that tbefluorescent component preferably should be already in the reactionmixture at the time of addition of the last component necessary to bringabout the chemical reaction and the concurrent release of chemicalenergy.

Additionally, it has been found that the superior intensity ofchemiluminescence is obtained when the final mixture producing theluminescence is maintained at a temperature of between about -40° and100°C., preferably between about 20° and 50°C; the luminescence ofApplicant's process is not limited to these ranges and temperature isnot critical.

Additionally, the composition and the process which obtains preferredoptimum chemiluminescent light intensity employs an acid in an amountsufficient to produce an acidic pH. However, the preferred extendedliftime is obtained under about neutral conditions. Any suitable acidwhich does not interfere with the chemiluminescent combination andprocess of this invention may be employed.

The preferred composition and the preferred process which obtainschemiluminescent light employs an acid in an amount sufficient toproduce an acidic pH. The acids that are effective include thosecompounds that are characterized by an acid ionization constant in watergreater than 1 × 10⁻ ⁸ as:

a) carboxylic acids e.g. formic acid, acetic acid, propionic acid,chloroacetic acid, dichloroacetic acid, trichloroacetic acid, benzoicacid, nitrobenzoic acid, dinitrobenzoic acid, oxalic acid, malonic acid;

b) phenols e.g.: dinitro-o-cresol, dinitrophenyl, picric acid;

c) sulfonic acids: e.g. benzenesulfonic acid, methanesulfonic acid,toluene-sulfonic acid;

d) inorganic acids: e.g. phosphoric, hydrochlorid, sulfuric, nitricacid.

However, the presence of acid is not essential to obtainchemiluminescence.

The lifetime and the intensity of the chemiluminescent light can beregulated by the use of certain regulators such as:

1. By the addition of acid to the chemiluminescent composition toincrease intensity and decrease lifetime, and by the addition of base todecrease intensity. Both the strength and the concentration of the baseare critical for purposes of exactness in regulation.

2. By the variation of hydroperoxide. Both the type and theconcentration of hydroperoxide are critical for the purposes ofexactness in regulation.

The following examples are intended to illustrate the present inventionand are in no way intended to limit the invention except at limited inthe appended claims.

EXAMPLE I Bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal ##SPC8##

Preparation: (New compound)

(2-hydroxypyridine (4.76 g, 0.05 mole) dried by azeotropic distillationwith benzene) is dissolved in 150 ml freshly distilled1,2-dimethoxyethene. To the stirred solution 2,2 ml (0.025 mole)oxalyl-chloride and 5.05 g (0.05 mole) triethylamine are added. After 1hour stirring the mixture is evaporated to dryness under vacuum and theresidue is warmed with two 25 ml portions of chloroform to obtain 7.5gof white solid. The product is recrystallized from benzene to obtain2.76 g (37.4%) of white crystals melting point 164° - 74°C.(d).

    ______________________________________                                        Analysis for C.sub.12 H.sub.8 N.sub.2 O.sub.y :                               C           H             N                                                   ______________________________________                                        calculated                                                                            59.02   calculated                                                                              3.30  calculated                                                                            11.47                                 found   59.08   found     3.31  found   11.46                                 ______________________________________                                    

Infrared absorption bends in the >c = o streching region taken in nujol:1742, 1712, 1672 cm⁻ ¹.

EXAMPLE II

The tests of Table I were carried out as follows:

A. approximately 3-5 mg. of the compound to be tested is added to a 5ml. solution of about 1 mg. DPA and 0.2 ml anhydrous H₂ O₂ in anhydrous1,2-dimethoxyethane maintained at 25°C.

B. approximately 3-5 mg. of the compound to be tested is added to a 5 mlslurry of 1 mg DPA, 0.2 g KOH (1 pellet) and 0.2 ml anhydrous H₂ O₂ inanhydrous 1,2-dimethoxyethane maintained at 25°C.

C. as test A except that approximately 0.1 ml water is added prior tothe addition of the compound being tested.

D. approximately 3-5 mg of the compound to be tested is added to a 5 mlsolution of 1 mg DPA and 0.2 ml CH₃ SO₃ H in 1,2-dimethoxy-ethanecontaining 5% water and maintained at 25° C. About 0.5 ml 30% H₂ O₂ isadded immediately.

Qualitative intensities are based on the oxalyl chloride, hydrogenperoxide reaction taken as strong (S). Other designations are M =medium; W = weak; VW = very weak, barely visible.

Qualitative chemuliminescence tests of the compound are shown in Table Ibelow.

                  TABLE I                                                         ______________________________________                                        Bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal Evaluation                            Variable Reactants   Illumination                                             Example            Other                                                      No.     Peroxide   Reactants Intensity                                                                             Lifetime                                 ______________________________________                                        II A    Anhydrous            Medium  Long                                             H.sub.2 O.sub.2                                                       II B    H.sub.2 O.sub.2                                                                          KOH       Weak    --                                       II C    H.sub.2 O.sub.2                                                                          H.sub.2 O Medium  Long                                     II D    H.sub.2 O.sub.2 (30%)                                                                    H.sub.3 O.sup.+                                                                         Strong  Medium                                   ______________________________________                                    

EXAMPLE III Infrared Study of the Acid Catalyzed Rearrangement ofBis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal to bis(-2-pyridyl)oxalate

A stock solution of 5.8 × 10⁻ ² molarbis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal in triethylphosphate isprepared, and the infrared spectrum of the solution is recorded from1900 to 1500 cm⁻ ¹. To 0.75 ml aliquots of the stock solution,containing 10.7 mg (4.3 × 10⁻ ⁵ moles) of glyoxal, is added,respectively, 6μ 1 (8.6 × 10⁻ ⁵ moles) of methanesulfonic acid, 1.6μ 1(2.9 × 10⁻ ⁵ moles) of phosphoric acid, and 7 μ 1 (8.6 × 10⁻ ⁵ moles) ofhydrochloric acid (37%), and the infrared spectra of the three solutionsare recorded from 1900 to 1500 cm⁻ ¹ to determine if rearrangement takesplace.

The results of the experiment show that the characteristic bands of thebis(1,2-dihydro-2-oxo-pyridyl)glyoxal at 1743, 1719, and 1680 cm⁻ ¹ intriethylphosphate solution are slowly diminished on the addition ofacids, and the experiments reveal the appearance of a band at 1808 cm⁻ ¹attributed to the formation of 2-pyridyl oxalate. The per centconversion of N-acyl to 0-acyl compound was determined as: 30% in thecase of methanesulfonic acid catalysis, and 5% in the cases both ofphosphoric and hydrochloric acids after 5 min. elapsed time.

Both a study using I.R. spectroscopy of Example III and the strongchemiluminescence obtained in the presence of methane sulfonic acid inTable I of Example II points to the conclusion thatbis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal undergoes an acid catalyzedrearrangement to bis(2-pyridyl)oxalate prior to the chemiluminescentreaction. It is the latter compound which produces chemiluminescence ina reaction with H₂ O₂ in the presence of a fluorescer.

EXAMPLE IV

The quantitative evaluation of the chemiluminescence ofbis(1,2-dihydro-2-oxopyridyl)glyoxal shown in Table I is carried out asfollows:

A. the reagents dissolved in dimethyl phthalate are mixed in a quartzcell provided with a magnetic stirrer. The order of mixing is asfollows: glyoxal, 9,10-diphenyl anthracene, methane sulfonic acid,hydrogen peroxide. The reaction mixture then contains 0.001 mole 1⁻ ¹bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal, 6 × 10⁻ ⁴ mole 1⁻ ¹9.10-diphenyl anthracene 3.3 × 10⁻ ⁴ mole 1⁻ ¹ methane sulfonic acid and0.1 mole 1⁻ ¹ hydrogen peroxide. The emitted strong chemiluminescentlight is measured by a radiometer-spectrophotometer at 25°C.

B. part B is conducted the same way as experiment A, except that ahigher, 0.01 mole 1⁻ ¹ concentration ofbis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal is used.

C. part C is conducted the same way as experiment B except that ahigher, 3.3 × 10⁻ ³ mole 1⁻ ¹ concentration of methane sulfonic acid isused.

D. part D is conducted the same way as experiment B except that 0.1 mole1⁻ ¹ phosphoric acid is used in the place of methane sulfonic acid.

                                      TABLE II                                    __________________________________________________________________________    The Effect of Acids on the Chemiluminescence Quantum Yield and Radiation      Capacity                                                                      of bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal yridyl)glyoxal in Dimethyl         Phthalate Solution                                                            Ex. IV                                                                              Acid      glyoxal                                                                              acid concen-                                                                           mole ratio                                                                          t.sub.1/4 I.sub.max *                                                                Quantum Radiation**              Part            (mole 1.sup.-.sup.1)                                                                 tration  (acid to                                                                            (min.) Yield   Capacity                 No.                    (mole 1.sup.-.sup.1 ×10.sup.4)                                                   ester)       (einstein                                                                             (einstein                                                                     1.sup.-.sup.1                                                                 ×                                                               mole.sup.-.sup.1 ×10.su                                                 p.2)    10.sup.4                 __________________________________________________________________________    A     Methane sulfonic                                                                        0.0010 3.3      0.33  2.0    12.9    1.3                      B     Methane sulfonic                                                                        0.0100 3.3      0.033 5.0    2.3     2.3                      C     Methane sulfonic                                                                        0.0100 33.0     0.330 <1.0   16.9    16.9                     D     Phosphoric (86%)                                                                        0.0100 1000.0   10.00 4.0    2.1     2.1                      __________________________________________________________________________     *The time required for the light intensity to decrease to one quarter of      its maximum value.                                                            **Represents the ability of the chemiluminescent system to emit visible       chemiluminescent light.                                                  

EXAMPLE V

The chemiluminescence of bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal isqualitatively studied in five solvents or solvent mixtures in thepresence of three different fluorescers. The results are shown in TableIII.

In Parts A and G of this Example, approximately 3-5 mg. of the compoundto be tested is added to a 5 ml. solution of about 1 mg DPA and 0.2 mlanhydrous H₂ O₂ in the indicated anhydrous solvent maintained at 25°C.

In Parts B and H of this Example, approximately 3-5 mg of the compoundto be tested is added to a 5 ml slurry of 1 mg DPA, 0.2 g KOH (1 pellet)and 0.2 ml anhydrous H₂ O₂ in the indicated anhydrous solvent maintainedat 25°C.

Part C of this Example is carried out as test A, except thatapproximately 0.1 ml water is added prior to the addition of thecompound being tested.

In Parts D, E and I of this Example, approximately 3-5 g of the compoundto be tested is added to a 5 ml solution of 1 mg DPA and 0.2 ml CH₃ SO₃H in the indicated solvent maintaining at 25°C. About 0.2 ml 98% H₂ O₂is added immediately.

Part J is carried out as test A except 30% aqueous H₂ O₂ is used.

Part L is carried out as test B, except 30% aqueous H₂ O₂ is used.

Part K is carried out as test A, except 30% aqueous H₂ O₂ is used.

Part M is carried out as test I, except 0.4 ml concentrated HCl is usedin the place of methanesulfonic acid and 30% H₂ O₂ is used in the placeof 98% H₂ O₂.

EXAMPLE VI

The superior light producing capability of thebis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal is demonstrated in Table IV.

All chemiluminescent measurements shown in Table IV are carried out bythe use of a radiometer-spectrophotometer on a solution of 0.01 mole 1⁻¹ of the chemiluminescent compound and 6 × 10⁻ ₄ mole 1⁻ ¹9,10-diphenylanthracene at 25°C. The other reagents and solvent usedvary as shown below:

1. The experiments are carried out in dimethyl phthalate solution in thepresence of varying amounts of hydrogen peroxide as follows:

a. The hydrogen peroxide persent is 0.024 mole 1⁻ ¹.

b. The hydrogen peroxide present is 0.090 mole 1⁻ ¹.

2. The experiment is carried out in dimethyl phthalate solution in thepresence of 0.024 mole 1⁻ ¹ hydrogen peroxide.

3. The experiment is carried out in dimethyl phthalate solution in thepresence of varying amounts of hydrogen peroxide as follows:

a. The hydrogen peroxide concentration is 0.024 mole 1⁻ ¹.

b. The hydrogen peroxide concentration is 0.09 mole 1⁻ ¹.

c. The hydrogen peroxide concentration is 0.09 mole 1⁻ ¹, but 8.3 × 10⁻⁴ mole 1⁻ ¹ triethylamine is also present.

4. The experiment is carried out in triethyl phosphate solution in thepresence of 0.018 mole 1⁻ ¹ hydrogen peroxide.

5.

a. The experiment is carried out in dimethyl phthalate solution in thepresence of 0.09 hydrogen peroxide.

b. The experiment is carried out in 1,2-dimethoxyethane solution in thepresence of 0.042 mole 1⁻ ¹ hydrogen peroxide.

c. The experiment is carried out in dimethyl adipate solution in thepresence of 0.099 mole 1⁻ ¹ hydrogen peroxide.

6. The experiment is carried out in dimethyl phthalate solution in thepresence of 0.064 mole 1⁻ ¹ hydrogen peroxide and 0.0037 mole 1⁻ ¹methane sulfonic acid.

                                      TABLE III                                   __________________________________________________________________________    Bis(2-pyridyl)oxalate Evaluation                                              Ex. V                                                                              Reaction Conditions           Results                                    Part                               Inten-                                                                             Life-                                      Solvent Fluorescer                                                                          Peroxide                                                                            Base                                                                              Acid  sity*                                                                              time                                  __________________________________________________________________________    A    1,2-di- 9,10-di-                                                                            anhydrous                                                                           --  --    M    long                                       methoxy-                                                                              phenyl-                                                                             H.sub.2 O.sub.2                                            B    ethane  anthracene                                                                          H.sub.2 O.sub.2                                                                     KOH --    W    long                                       (DME)   (DPA)                                                            C                  aqueous                                                                             --  --    M    long -                                                                            H.sub.2 O.sub.2                   D                  H.sub.2 O.sub.2                                                                     --   H.sub.3 O.sup.+**                                                                  VW   Medium                                E            Rubrene                                                                             H.sub.2 O.sub.2                                                                     --  H.sub.3 O.sup.+                                                                     VW   Fast                                  F    DME/H.sub.2 O(1:1)                                                                    DPA   aqueous                                                                             KOH --    None --                                                       30% H.sub.2 O.sub.2                                        G    dimethyl-                                                                             DPA   anhydrous                                                                           --  --    M - W                                                                              long                                       phthalate     H.sub.2 O.sub.2                                            H            DPA   H.sub.2 O.sub.2                                                                     KOH --    W    long                                  I            DPA   H.sub. 2 O.sub.2                                                                    --H.sub.3 O.sup.+                                                                 S     fast                                       J    acetic acid                                                                           DPA   30% H.sub.2 O.sub.2                                                                 --  --    S    long                                  K            disodium                                                                            30% H.sub.2 O.sub.2                                                                 --  --    None --                                                 fluorescein                                                      L    water         30% H.sub.2 O.sub.2                                                                 KOH --    None --                                    M            N-methyl-                                                                           30% H.sub.2 O.sub.2                                                                 --HCl                                                                             None  --                                                      acridinium                                                                    chloride                                                         __________________________________________________________________________     *Qualitative intensities are based on the oxalyl chloride, hydrogen           peroxide reaction taken as strong [S]. Other designations are M = medium;     W = weak; VW = very weak, barely visible.                                     **Acetic acid was used in the place of methane sulfonic acid.            

                                      TABLE IV                                    __________________________________________________________________________    Summary of High Radiation Capacities                                          No.                                                                              Chemiluminescent Compound                                                                         Solvent*                                                                            Hydrogen-                                                                            Radiation Capacity**                                                                      t.sub.1/4 I.sub.max ***                                    Peroxide                                                                             (einstein 1.sup.-.sup.1 ×10.sup.                                        2)                                                                     (mole 1.sup.-.sup.1)                             __________________________________________________________________________    1  Bis(2,4-dinitrophenyl)oxalate                                                 a)                  DMP   0.024  8.5         3                                b)                  DMP   0.090  8.1         12                            2  Bis(2,4-dinitro-6-methylphenyl) DMP                                                               0.024 7.1    2                                            oxalate                                                                    3  Bis(2-formyl-2-nitrophenyl)oxalate                                            (a)                 DMP   0.024  8.7         89                               b)                  DMP   0.090  8.0         75                               c)                  DMP   0.090.sup.d                                                                          7.0         20                            4  Bis(3-trifluoromethylphenyl)oxalate                                                               TEP   0.018  7.2         26                            5  Bis(pentafluorophenyl)oxalate                                                 a)                  DMP   0.090  7.6         58                               b)                  DME   0.042  9.7         6                                c)                  DMA   0.099  8.1         20                            6  Bis(1,2-dihydro-2-oxo-1-pyridyl)                                                                  DMP   0.064  16.9        <1                               glyoxal                                                                    __________________________________________________________________________     *DMP is dimethyl phthalate, DME is 1,2-dimethoxyethane, DMA is dimethyl       adipate, TEP is triethyl phosphate.                                           **Time required for the light intensity to decrease to 1/4 of its maximum     value.                                                                        ***Represents the ability of the chemiluminescent system to emit              chemiluminescent light.                                                  

EXAMPLE VII

The preparation of bis(5-oxo-1,5-dihydro-1-quinol)glyoxal is carried outthe same way as that described in Example I forbis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal except 5-hydroxy quinoline isused in the place of 2-hydroxy pyridine.

It is within the scope of this invention to make such modifications ofthe compositions and processes disclosed herein as would be obvious to aperson of ordinary skill in this art, and it is to be understood thatthe examples illustrating this invention are intended to limit theinvention only insofar as is stated in the specification and as thefollowing claims are limited. Also, it is within the scope of thisinvention to form an apparatus or article such as a container which, forexample, may be either (1) a substantially insoluble or alternatively(2) a dissolvable capsule in which the reactant or composition of thisinvention is substantially enclosed for subsequent reaction with otheringredients necessary to produce chemiluminescent light.

EXAMPLE VIII

Bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal is tested for chemiluminescencein a reaction with hydroperoxides other than hydrogen peroxide. Thetests carried out are as follows:

A. Approximately 3 mg glyoxal is added to a 5 ml solution of 1 mg DPAand 25 mg peroxy-4-nitrobenzoic acid in 1,2-dimethoxyethane (DME)maintained at about 25%. No substantial chemiluminescence is observed.

B. Test is similar to test A except 0.2 g KOH is also added. No.substantial chemiluminescence is observed.

C. Test is similar to test A except 0.1 ml water is also added. Nosubstantial chemiluminescence is observed.

D. Test is similar to test A except 0.1 ml methanesulfonic acid is alsoadded. Medium weak chemiluminescence is observed.

EXAMPLE IX

Tests described in Example VIII are repeated but t-butylhydroperoxide isused in the place of peroxy-4 -nitro benzoic acid. The results of thetests are as follows:

A. no substantial chemiluminescence is observed.

B. no substantial chemiluminescence is observed.

C. no substantial chemiluminescence is observed.

D. medium chemiluminescence is observed.

I claim:
 1. Bis(1,2-dihydro-2-oxo-1-pyridyl)glyoxal.